Documents leaked Sunday from a Panama-based firm, which sells offshore shell companies, purport to show corruption and questionable business practices of the world’s politicians, billionaires, entertainers, athletes, drug barons, and others.

At the heart of the nearly four decades of records from Mossack Fonseca, the Panamanian law firm, are the names of people in more than 200 countries and territories. The 11.5 million records reveal the offshore holdings of 12 current and former leaders—among them the Saudi king, the pro-Western president of Ukraine, and the leaders of Iceland and Pakistan.

The papers appear to show Mossack Fonseca helped its clients launder money, dodge sanctions, and avoid paying taxes. Offshore services are not always illegal, but the documents released Sunday appear to reveal a clandestine web of shell companies, their real owners concealed under layers of secrecy, and connections to firms in different tax havens. The individual or group behind the leak is unknown, but the documents were published by the International Consortium of Investigative Journalists, Süddeutsche Zeitung, the German newspaper, and several news organizations around the world, including the BBC, after a yearlong investigation.

Here are some key takeaways:

—A close associate of Russian President Vladimir Putin and Bank Rossiya, a Russian bank that has been blacklisted by the U.S. and the EU, laundered hundreds of millions of dollars, the documents allege. The associate in question is Sergey Roldugin, a classical cellist and conductor who is a childhood friend of the Russian president. “The records show Roldugin is a behind-the-scenes player in a clandestine network operated by Putin associates that has shuffled at least $2 billion through banks and offshore companies,” the ICIJ alleges. “In the documents, Roldugin is listed as the owner of offshore companies that have obtained payments from other companies worth tens of millions of dollars. … It’s possible Roldugin, who has publicly claimed not to be a businessman, is not the true beneficiary of these riches. Instead, the evidence in the files suggests Roldugin is acting as a front man for a network of Putin loyalists—and perhaps for Putin himself.” The Russian president is never named in the files. A Kremlin spokesman denied the allegations as “a series of fibs.” Roldugin, ICIJ said, did not respond to questions about his alleged actions.

—Among the world leaders named in the papers is  Petro Poroshenko, Ukraine’s pro-Western president. The documents allege that at the height of Russia’s invasion of his country in 2014, Poroshenko “scrambled to find a copy of a home utility bill for him to complete the paperwork to create a holding company in the British Virgin Islands.” A representative for Poroshenko denied the move was connected to “any political and military events in Ukraine.” The firm was not included in Poroshenko’s financial disclosure that year—a move his financial advisers said was because the holding company didn’t have any assets. “They said that the companies were part of a corporate restructuring to help sell Poroshenko’s confectionery business,” ICIJ reported.

—Also named is Sigmundur Gunnlaugsson, Iceland’s prime minister, who was elected after that country’s financial collapse. The documents allege Gunnlaugsson hid millions of dollars of investments in his country’s banks in an offshore company. Gunnlaugsson and his wife, Anna Sigurlaug Palsdottir, bought the company in 2007, but he failed to declare his interest in it when he entered parliament two years later. The documents show Gunnlaugsson later sold half the company to his wife for $1. The prime minister denies any rules were broken, but he is facing calls for his resignation.

—The documents also reveal offshore companies linked to the family of Xi Jinping, China’s president who has cracked down on corruption in the country. Mossack Fonseca, the papers allege, has “serviced enough Middle East royalty to fill a palace. It’s helped two kings, Mohammed VI of Morocco and King Salman of Saudi Arabia, take to the sea on luxury yachts.” The papers also appear to show secret offshore companies linked to the families and associates of Hosni Mubarak, the former Egyptian president, Muammar Qaddafi, the former Libyan leader, and Syrian President Bashar al-Assad.

For further reading:

Giant Leak of Offshore Financial Records Exposes Global Array of Crime and Corruption

The Power Players

Inside the Secretive World of Tax-Avoidance Experts

What Can We Do With Our Shell Companies?